TUBER

KELOMPOK 4AET 1

• CHRISTIAN NATANAEL TARIGAN / 090301003• FADMA JUWITA NASUTION / 090301002• DINA ARSYI FAZRIN / 090301020• EVI JULIANITHA HARAHAP / 090301022• BAYHAQI / 090301023• SISKO BUDIANTO / 090301029• KUKUH IMAN BUDIONO / 090301030• NIKKO SEPTIAN FAZILLA / 090301033• MUHAMMAD RIZKI SIREGAR / 090301041• ACHMAD HAMBALI NASUTION / 090301053

Tuber Organ tanaman yang membengkak,

modifikasi dari struktur batang atau akar yang berfungsi sebagai sebuah organ penyimpanan di bawah tanah.

Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction. Two different groups of tubers are: stem tubers, and root tubers.

Faktor-faktor yang Mempengaruhi Pembentukan Umbi/Tuber :

- Suhu (15-200 C)

suhu optimum 15,6-17,80 C.- Kelembaban Udara (80-90%)- Panjang Hari (10-16 jam per hari)- Suhu Tanah- Tanggal Tanam- Umur Fisiologis Umbi- Karakteristik Budidaya Umbi yang dilakukan

Tuberous Stem

A stem tuber forms from thickened rhizomes or stolons. The tops or sides of the tuber produce shoots that grow into typical stems and leaves and the under sides produce roots. They tend to form at the sides of the parent plant and are most often located near the soil surface. The below-ground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant.

Stem tubers generally start off as enlargementof the hypocotyl section of a seedling but also sometimes include the first node or two of the epicotyl and the upper section of the root. The stem tuber has a vertical orientation with one or a few vegetative buds on the top and fibrous roots produced on the bottom from a basal section, typically the stem tuber has an oblong rounded shape.

Contoh Tanaman Tuberous Stem

Kentang (Solanum tuberosum L.)

Plectranthus esculentus

Anredera cordifolia

Begonia

Anatomy of Tuberous Stem

The tuber has all the parts of a normal stem, including nodes and internodes, the nodes are the eyes and each has a leaf scar. The nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon. The terminal bud is produced at the farthest point away from the stolon attachment and tuber thus shows the same apical dominance of a normal stem. Internally a tuber is filled with starch stored in enlarged parenchyma like cells; also internally the tuber has the typical cell structures of any stem, including a pith, vascular zones and a cortex.

• Tuber eye The buds from which next season's growth will emerge. Eyes are concentrated near the apical end of the tuber, with fewer near the stolon or basal end. Eye number and distribution are characteristic of the variety

• Tuber skin Tuber skin is composed of two layers of cells: an outer layer of single cells called the epidermis, underlain by several layers of corky cells called the periderm. The periderm layer may contain a pigment that produces coloured potatoes.

• Tuber cortex Tissue between skin and a vascular ring. • Vascular ring Vascular ring contains cells that transport

nutrients from the above ground stems to the medulla. • Tuber medulla Medulla represents the primary storage

area for the potato tuber. • Tuber perimedulla Is located between the vascular ring and

medulla.

Tuberous Root

Umbi akar (tuberous root) adalah modifikasi akar lateral, mengalami pembesaran yang berfungsi sebagai organ penyimpanan. Secara harfiah ini berbeda tetapi sama dalam fungsi dan penampilan pada tuber/umbi yang sebenarnya. Sebagai contoh tanaman dengan umbi akar yang jelas adalah sweet potato (ketela rambat), cassava dan dahlia. Sebuah umbi akar membuat tanaman untuk bertahan dari tahun ke tahun.

The life cycle of a potato tuber is characterized by initiation and growth followed by a period of dormancy and finally sprouting resulting in the next (vegetative) generation.

• Sprouting tuber Growth stage 1. The onset of sprout growth that follows dormancy termination is accompanied by substantial increases in cell metabolism; sprouts appear from the eyes of the primary tuber.

• Vegetative Growth stage 2. Plant establishment. All vegetative parts of the plants (leaves, branches, roots and stolons) are formed; stages 1 and 2 last from 30 to 70 days depending on planting date, soil temperature and other environmental factors, the physiological age of the tubers, and the characteristics of particular cultivars.

• Tuber initiation Growth stage 3. Approximately 30-60 days after the seed tuber is planted, tuber formation begins. Tubers are derived from lateral underground buds developing at the base of the main stem that when kept underground develop into stolons due to diagravitropical growth. When the conditions are favorable for tuber initiation, the elongation of the stolon stops, and cells located in the pith and the cortex of the apical region of the stolon first enlarge and then later divide longitudinally. The combination of these processes results in the swelling of the subapical part of the stolon.

• Developing tuber Growth stage 4. During enlargement tubers become the largest sink of the potato plant storing massive amounts of carbohydrates (mainly starch) and also significant amounts of protein. Furthermore, tubers decrease their general metabolic activity and as such behave as typical storage sinks.

• Mature tuber Growth stage 5. Potato tubers are harvested from 90 to 160 days after planting and this may vary with cultivars, production area, and marketing conditions. Starch the typically represents 20% of the fresh weight of mature tuber. After potato vines die back the skin of tuber thickens and hardens, which provides greater protection to tubers during harvest and blocks entry of pathogens to the tuber.

• Dormant tuber Although dormancy is defined as the absence of visible growth, dormant meristems are metabolically active. In general, rates of many cellular processes such as respiration, transcription, and translation are suppressed during dormancy. Non-dividing, dormant tuber meristems are arrested in the G-1 phase

KESIMPULAN1. Tuber adalah organ tanaman yang membengkak, modifikasi

dari struktur batang atau akar yang berfungsi sebagai sebuah organ penyimpanan di bawah tanah.

2. Tuber merupakan modifikasi dari stolon yang membengkak, karena berisi pati (starch) atau cadangan makanan.

3. Faktor-faktor yang mempengaruhi pembentukan umbi adalah suhu udara, kelembaban udara, suhu tanah, tanggal tanam, umur fisiologis umbi, panjang hari dan teknik budidaya.

4. Umbi/tuber terbagi dua yaitu umbi batang (tuberous stem) seperti kentang (Solanum tuberosum L.), dan umbi akar (tuberous root) seperti sweet potato (Ipomea batatas L.).

5. Daur umbi terbagi enam yaitu sprouting tuber, vegetatif growth, tuber initiation growth, develoving tuber growth, mature tuber growth dan dormant tuber.

TERIMA KASIH